This invention generally relates to vascular procedures such as angioplasty, and more particularly to an extendable guidewire for use in such procedures.
Guidewires are currently used to facilitate the placement of catheters in the arterial system of a patient for cardiovascular procedures such as angioplasty. The guidewire is typically on the order of 20-50 cm longer than the catheter to permit the guidewire and the catheter to be advanced relative to each other as they are steered into position within the patient's body. Suitable guidewires are described in U.S. Pat. No. 4,538,622 (Samson et al.) and U.S. Pat. No. 4,569,347 (Frisbie) which are hereby incorporated herein in their entirety.
If the deflated balloon on the dilatation catheter is too large to pass through a stenosis, then the catheter must be exchanged for one having a lower deflated profile. In the usual procedure to change catheters, the guidewire is removed from the patient, and an exchange wire is inserted in its place. The in-place catheter is then removed from the patient and a new catheter is inserted into the patient over the exchange wire. The exchange wire is then removed an the guidewire is reinserted. The exchange wire is substantially longer than the guidewire, and it generally extends outside the patient's body for a distance greater than the length of the catheter. With a dilatation catheter having a length on the order of 80 cm, for example, a guidewire might have a length on the order of about 100 to 175 cm, and an exchange wire might have a length on the order of about 200 to 300 cm. The use of an exchange wire has the obvious disadvantage that it complicates the angioplasty procedure.
Heretofore, there have been some attempts to eliminate the need for a separate exchange wire by attaching an extension wire to a guidewire to extend the length thereof. The two wires are joined together by a crimped connector which requires a special tool. Once the wires have been crimped, the connection therebetween is permanent, and the extension wire cannot be removed except by severing it from the guidewire. Prior extendable wires for use in coronary angioplasty procedures have been found to be no very suitable in peripheral arteries because the connections are not strong enough.
What has been needed and heretofore unavailable is a strong guidewire extension which can be readily connected and disconnected to the guidewire when it is in position within the patient. The present invention satisfies this need.